TNF-α: a treatment target or cause of sarcoidosis?

Sarcoidosis is a systemic granulomatous disease that affects numerous organs, commonly manifesting at the lungs and skin. While corticosteroids remain the first line of treatment, tumour necrosis factor alpha (TNF-α) inhibitors have been investigated as one potential steroid sparing treatment for sarcoidosis. TNF-α is one of many components involved in the formation of granulomas in sarcoidosis. While there have been larger scale studies of biologic TNF-α inhibition in systemic sarcoidosis, studies in cutaneous disease are limited. Paradoxically, in some patients treated with biologic TNF-α inhibitors for other diseases, treatment can induce the development of sarcoidosis. In the light of this complexity, we discuss the role of TNF-α in granuloma formation, the therapeutic role of TNF-α inhibition and immunologic abnormalities following treatment with these TNF-α inhibitors including drug-specific alterations involving interferon-γ, lymphotoxin-α, TNF receptor 2 (TNFR2) and T-regulatory cells.